Packaging apparatus for providing packaging for products of various sizes is known. A representative sample of this apparatus is discussed below.
U.S. Pat. No. 3,553,934 (Johnson) discloses machinery that makes bags of different widths and lengths from folded film dispensed by a single dispenser.
Unfortunately, there are a few problems with this apparatus. If products are of varying sizes, then the depth of the folded film must be such that larger bags for accommodating larger products can be made. However, when smaller bags are cut from the film there is considerable wastage.
U.S. Pat. No. 4,179,055 (Milner) discloses a device having several supply rolls each having continuous strip of plastic material in the form of bags connected to each other at scored lines. The bags are of differing size from roll to roll. A problem with this device is that there is no flexibility provided by the user in choosing bag length. Only discrete lengths are available according to which supply roll is chosen. Thus, it is possible that products of greater length than average could not be provided with a bag of sufficient size to contain the products. Alternatively, there may be considerable wastage occurring as a result of only discrete lengths being able to be chosen.
A similar problem is present in the apparatus disclosed in U.S. Pat. No. 4,425,988 (Amplas, Inc). This discloses apparatus that makes bags of varying lengths from tubular lay flat film. However, the width of the tubular lay flat film restricts the overall bag size and variations that can be offered. Again wastage occurs.
U.S. Pat. No. 4,505,092 (Hobart Corporation) discloses apparatus which addresses the wastage problem. This apparatus has two film dispensers containing stretch wrap film of different widths. Product passes through the apparatus prior to being packaged. If the product activates either a discrete height or width mechanical sensor, then the product is wrapped in the film having the greater width.
Unfortunately, this apparatus is not suitable for all situations. For the pack to be airtight seals must be formed through wrinkle-free areas of the film and show no weakness at the intersection of seals. Folding of film into a wrinkle free format suitable for airtight seals is relatively easy with regular rectangular shaped products but extremely difficult with irregular shaped products such as cuts of meat.
Often it is preferred to place product into a discrete sized package. If this package is made from shrink film, then the film can be heated to cause the film to shrink around the product, forming intimate contact which gives an anesthetically pleasing appearance to the packaged product.
Another problem with this apparatus is that it cannot be used for packaging as a post process. That is, the product must pass through the wrapping machine to be packaged. This is in contrast to packaging as a post process whereby the package is substantially formed before product is inserted into it.
It would be desirable if the packaging could be provided for products of varying size which are then later on placed in that packaging. This is particularly useful if the products are of a large size or awkward shape which cannot be readily fed through a packaging machine. Seals should be minimised providing for subsequent airtight (vacuum) packaging.
Yet another problem with the apparatus disclosed in U.S. Pat. No. 4,505,092 machinery is that the discrete mechanical sensors are only of value in selecting the width of film to be used when the products are of a regular shape. This is because an irregular shaped product may not trigger the mechanical sensors, yet still be of a size requiring the greater film width.
It is an object of the present invention to address the above problems, at least provide the public with a useful choice.
Further objects and advantages of the present invention will become apparent with the following description which is given by way of example only.